Spherical surface geometries are difficult to image with optical systems; especially with a single beam scanning architecture. Conventional digital image acquisition devices use focal plane arrays, but even with this technology it is difficult to achieve uniform illumination across the spherical surface without the use of highly complex and expensive mechatronics to move the source/detector pair along the curved target. In the terahertz and far-infrared regions, this challenge is accentuated due to a lack of a powerful illumination sources and practical, sensitive focal-pane arrays. Accordingly, there exists a need for improved methods and systems for imaging the surface of a spherical body.